i used lugol's solution from kent marine. coral rx and coral revive works well too.
for hardy corals like zoas, i dip using ro/di water. distilled water is fine too. i find there are more hiding places for the pests, and their pest more hardy too.
for other corals i dip in saltmix water, not aquarium water.
dip amount as instructed in the manual. (dip 40drips for 1 gallon/3.78 litre of water. i use 20 drips with 2 litre of water. if only 1 or 2 pieces of coral, if many corals then use more water and more drips. immerse the coral completely)
dip for 10-15mins, i keep shaking the coral, or use a pipette to jet it, blast those pest out.. remember to visually check for bad starfish or crab which are likely to cling on tightly to the coral.
but don't overdose. it will damage coral as well. i almost kill a rock of zoas. heng they very hardy, 2 days later then open up.